Within these projects and alone, he has collaborated with a variety of musical artists, including Greg Anderson, Scott Walker, Merzbow, Eyvind Kang, Alan Moore, Iancu Dumitrescu, Ana-Maria Avram, Alvin Lucier, F.M.
Einheit, Randall Dunn, James Plotkin, Julian Cope, Joe Preston, Attila Csihar, Stuart Dempster, Mika Vainio, Peter Rehberg, Lee Dorian, Thurston Moore, Jóhann Jóhannsson, Nurse With Wound, Boris, Michio Kurihara, Jim O'Rourke, Keiji Haino, Daniel O'Sullivan & Kristoffer Rygg (in the free improvisation act Æthenor together with Vincent de Roguin and Steve Noble), Aaron Turner, David Tibet, Oren Ambarchi, Alexander Tucker, Z'EV, and more recently with Senyawa, Félicia Atkinson, Kali Malone, and François J.
[2] O'Malley also produced work together with the Franco-Austrian choreographer and director Gisèle Vienne on the pieces Kindertotenlieder (2007), Jerk (2008), Eternelle Idole (2009), This Is How You Will Disappear (2010),[3] Last Spring: A Prequel (2011), The Pyre (2013) and L'Etang (2021).
He has also worked with American sculptor Banks Violette (various projects between 2005–2009), the Italian performance artist Nico Vascellari (2007–2011), Swiss art collective KLAT (2009), and the Belgian film maker Alexis Destoop (Kairos with Oren Ambarchi, 2010).
[citation needed] O'Malley has designed record covers since the early 1990s for groups such as Earth, Burzum, Emperor, Mayhem, Gehenna, Boris, Dissection, Oneohtrix Point Never, and Cathedral.